Well, it's not entirely what you think it is.
I haven't seen any analytics that tracks scrolling (not that that may not exist) BUT yes, even good 'ol google analytics tracks time spent on each page. And that has been that case for probably a decade and is completely normal in this day and age.
It's helpful for marketing (ROI), determining which page and content may need improvement, if there is a bug on the site. Like just a few days ago, I noticed my bounce rate (so not going past the home page) was high for both sites. Turns out some code was slowing down the loading of them. Removed the code, added a new widget and it was fixed. I've also had to block a few visitors who based on the longevity of their visits, I am talking years or far, far more than my "norm", it was apparent they were stuck in fantasy mode, which makes me very uncomfortable.
There are certain details that aren't available by law but if the idea of any of that freaks you out, you shouldn't be online because it's everywhere nowadays.
Like London, I NERD OUT over analytics and know my business and clients who convert to an appointment patterns like the back of my hand.
P411 analytics are very basic: date, state, number of visits from that state that day and member/non-member. All I know is that I haven't booked one appointment off of P411 this year so that's the only analytic that matters to me.